1. Field of the Invention
This invention pertains to a tool for internal combustion engines and more particularly to a tool used to adjust the timing chain of such engines.
2. General Background
As is well known, for an internal combustion engine to run smoothly, the rotation of the crankshaft and the camshaft must remain in synchronization. Should they fall out of synchronization, serious damage can occur to the engine.
Generally, a timing chain is employed on a crank shaft gear mounted on the crank shaft to drive a cam shaft gear mounted on the cam shaft. This timing chain thus serves the purpose of not only causing the cam shaft to rotate, but it also maintains the rotational synchronization of these two shafts. However, as is also well known, it is not uncommon for the timing chain to slip ever so much such that the two shafts are no longer fully synchronized. If the slippage is small, no serious damage to the engine will occur other than decreased performance. However, if this slippage is great, a considerable amount of damage can occur. This is because when the cam shaft is not rotated to operate the valves during the cycle exactly when the valves must be operated (which depends upon the angular rotation of the crank shaft), the engine will not operate efficiently, the engine cylinders will not fill up and exhaust as needed resulting in a substantial loss of power, and mechanical breakdown will occur.
Consequently, when correcting the slippage of a timing chain, or when otherwise overhauling or rebuilding the engine for other reasons, a simple means of aligning the two gears, and hence the shafts, is needed. Caution must be taken to prevent the timing chain from simply being inserted around the two gears without also taking into account the relative position of these two gears. For proper installation, one or both of the shafts must be manually rotated and aligned with the other before the timing chain is installed to insure that their continued rotation after the engine is assembled remains synchronized. Oftentimes, to aid in the proper synchronization of the two shafts, marks are imprinted on their respective gears that must be aligned with each other before the timing chain can be installed.
Few devices currently exist which assist the mechanic in properly orienting the gears prior to installing the timing chain. There are even fewer devices which permit the mechanic to check whether such installation has been completed properly and/or which ascertain the degree to which the two gears (and hence shafts) are out of alignment in order to determine whether they need to be re-aligned.
U.S. Pat. No. 2,522,283 issued to Lamkin pertains to a self aligning measuring gauge that can determine the throw or eccentricity of the crank pins of a crank shaft or a cam shaft. This device measures the distance between the longitudinal axis of a shaft and the outermost eccentricity of its cam.
U.S. Pat. No. 5,007,302 issued to Chen pertains to a measuring gauge that checks the alignment of a cam mounted on or disposed around a cam shaft. It's protractor-like indica and grooves which are formed both longitudinally and transverse to the axis of the shaft aid in properly aligning the cams on the shaft.
U.S. Pat. No. 4,218,939 issued to Castoe pertains to a tool used to remove the cam shaft sprocket from the cam shaft. This tool retains the alignment of the timing chain with respect to the lower crank shaft such that the engine can still be cranked even though the cylinder head is removed.
U.S. Pat. No. 4,502,233 issued to Boitz, et al., pertains to a device for checking the alignment of a shaft in a turbine-to-compressor drive mechanism.
U.S. Pat. No. 4,723,517 issued to Frost pertains to a cam drive mechanism that is driven in such a manner as to impose a variable oscillation to the cams. This has the effect of varying the period during which an associated valve is opened.
U.S. Pat. No. 5,199,182 issued to Fowler pertains to a means of aligning the shafts of adjacent drive and driven machinery in order to insure that proper angularity and parallelism has been achieved.
While each of the above mentioned devices pertain to automotive and/or engines in general, none of them aid a mechanic in obtaining the proper alignment between a crank shaft and a cam shaft. It is thus an object of this invention to provide a means of assisting a mechanic in properly installing a timing chain. Another feature of this invention is its ability to quickly ascertain whether a cam shaft is synchronized with the crank shaft or not. Still another object of this invention is to provide a tool that can be quickly and easily inserted upon the crank shaft for an immediate visual indication as to whether the crank shaft gear and the cam shaft gear are properly aligned thereby permitting the subsequent installation of the timing chain. These and other objects and advantages of this invention will become obvious upon further investigation.